LUMBRICUS. 



Alimentary. 



which a long thin oesophagus passes back to the thin-walled 

 crop. Upon the oesophagus are three pairs of pouches, the 

 two hinder pair being known as calciferous 

 glands. The crop leads into the muscular 

 gizzard.^ which has a small opening into the long intestine. 

 A fold of the dorsal wall, called the typhlosole^ projects into 

 the lumen of the intestine. The alimentary canal is held in 

 position by a complete series of transverse septa dividing the 

 coelom into compartments. Each septum has an aperture 

 by wdiich coelomic fluid can pass from one segment to the 

 other. 



Fig. 127. — Transverse Section of an Earthworm in the 

 Inte:^tinal Region. (Semi-diagrammatic.) 



Yellow Cells. 



Ectoderm. 



Cuticle, 



Dorsal Pore. 



Dorsal Blood-vessel. 

 Typhlosole. 



Intestine. 



Setae. 



Longitudinal 

 Muscles. 



Nerve Cord. 



Ventral Blood-vessel. 



Under the ectoderm is a layer of connective tissue 

 beneath which lies a series of circular muscles. 



Muscular. 



Inside this there is a longitudinal series. These 



function very much as in Arenicola. 



The ccelomic fluid is nutritive and the coelom is spacious. 

 The coelomic w^all covering the intestine is thickened into a 

 mass of excretory yelloiv cells. The blood-vascular system 

 Blood- ^^ ^^^y ^^ ^^^' ^^^ ^^ blood (mainly respiratory) 

 ^ is bright red from the presence of hcemoglobin 



(cf. Arenicola). There is a main dorsal vessel 

 running forwards and a ventral backwards. These are con- 

 nected by numerous circular vessels, of which six at the 



